VStack content top is cut off

I'm trying to understand the following very simple view hierarchy:

Code Block swiftstruct BugScreenSpacing: View {
    var body: some View {
        VStack {
            Button("This", action:{})
            Button("takes", action:{})
            Button("a lot", action:{})
            Button("of space", action:{})
        }
    }
}

Code Block swift
struct BugScreenSpacing: View {
var body: some View {
VStack {
Button("This", action:{})
Button("takes", action:{})
Button("a lot", action:{})
Button("of space", action:{})
}
}
}

This is cut off at the top.

If I add a spacer and choose to ignore the bottom safe area, the content is still cut off at the top, and even executes the Spacer!

Code Block swiftstruct BugScreenSpacing: View {
    var body: some View {
        VStack {
            Button("This", action:{})
            Spacer()
            Button("takes", action:{})
            Button("a lot", action:{})
            Button("of space", action:{})
        }.edgesIgnoringSafeArea(.bottom)
    }
}

Code Block swift
struct BugScreenSpacing: View {
var body: some View {
VStack {
Button("This", action:{})
Spacer()
Button("takes", action:{})
Button("a lot", action:{})
Button("of space", action:{})
}.edgesIgnoringSafeArea(.bottom)
}
}

As soon as I put that into a scrollview, it behaves as expected – full code including previews below:

Code Block swiftimport SwiftUI
struct BugScreenSpacing: View {
    var body: some View {
        VStack {
            Button("This", action:{})
            Spacer()
            Button("takes", action:{})
            Button("a lot", action:{})
            Button("of space", action:{})
        }.edgesIgnoringSafeArea(.bottom)
    }
}
struct BugScreenSpacing_Previews: PreviewProvider {
    
    static var previews: some View {
        Group {
            BugScreenSpacing()
                .previewDevice("Apple Watch Series 6 - 40mm")
            ScrollView{
                BugScreenSpacing()
            }
            .previewDevice("Apple Watch Series 6 - 40mm")
            //Does not depend on device size:
            BugScreenSpacing()
                .previewDevice("Apple Watch Series 6 - 44mm")
            ScrollView{
                BugScreenSpacing()
            }
            .previewDevice("Apple Watch Series 6 - 44mm")
        }
    }
}

Code Block swift
import SwiftUI

struct BugScreenSpacing: View {
var body: some View {
VStack {
Button("This", action:{})
Spacer()
Button("takes", action:{})
Button("a lot", action:{})
Button("of space", action:{})
}.edgesIgnoringSafeArea(.bottom)
}
}

struct BugScreenSpacing_Previews: PreviewProvider {

static var previews: some View {
Group {
BugScreenSpacing()
.previewDevice("Apple Watch Series 6 - 40mm")

ScrollView{
BugScreenSpacing()
}
.previewDevice("Apple Watch Series 6 - 40mm")

//Does not depend on device size:

BugScreenSpacing()
.previewDevice("Apple Watch Series 6 - 44mm")

ScrollView{
BugScreenSpacing()
}
.previewDevice("Apple Watch Series 6 - 44mm")
}
}
}

What is happening here? How to correctly use the full available space, and rather are cut at the bottom than at the top?